Counsel representing Eugene Klein, a Roman Catholic priest who worked as a prison chaplain in Springfield, Mo., cited Prof. Trachtenberg’s article in a discussion of the proper scope of the “coconspirator statement” exception to the hearsay rule. Among other things, Klein is charged with helping Chicago mobster Frank Calabrese, who died in December 2012 while serving a life sentence for multiple murders, recover a valuable violin reportedly hidden in a Wisconsin house to keep the government from selling it.